diff --git a/pg4wp/core.php b/pg4wp/core.php
index 8422ad7..72d2a75 100644
--- a/pg4wp/core.php
+++ b/pg4wp/core.php
@@ -34,5 +34,5 @@ define( 'WP_USE_EXT_MYSQL', true);
 eval( str_replace( array_keys($replaces), array_values($replaces), file_get_contents(ABSPATH.'/wp-includes/wp-db.php')));
 
 // Create wpdb object if not already done
-if (! isset($wpdb))
+if (! isset($wpdb) && defined('DB_USER'))
 	$wpdb = new wpdb2( DB_USER, DB_PASSWORD, DB_NAME, DB_HOST );